Minimum separation between PSR and Rachio 3 controller

I’m changing my sprinkler system from a Intermatic controller with an Indexing valve to Rachio 3 with solenoid valves. I read an article saying there needs to be a 15’ minimum separation between the Pump Start Relay and the Rachio 3 controller due to possible interference problems. Is this true. I have space limitation where my pump is located. Can someone help me?

I’m having problems with a Rachio 3 controller installed 1 foot away from the pump switch relay. My schedule will run if I do a “schedule quick run”, but it won’t run from the calendar. Rachio tech support said this was due to interference from the relay and I should move the controller 15+ feet away.